He is the one who is vast with respect to His Attributes and qualities and those things linked to them - this from the point of view that none can enumerate His praise as He deserves, rather He is as He has praised Himself. Vast in grandeur, authority and dominion, vast in bestowing grace and good, great in majesty and nobility.
“The likeness of those who spend their wealth in the Way of Allah, is as the likeness of a grain (of corn); it grows seven ears, and each ear has a hundred grains. Allah gives manifold increase to whom He pleases. Allah is Wasi', the All-Knowing.”
[al-Baqarah (2): 261]
“O you who believe! Whoever from amongst you turns back from his religion, Allah will bring about a people whom He will Love, and they will love Him; humble towards the believers, stern towards the disbelievers, fighting in the Way of Allah and never afraid of the blame of the blamers. That is the Grace of Allah which He bestows on whom He Wills. Allah is Wasi', the All-Knowing.”
[al-Ma'idah (5): 54]
From “Explanation to the Beautiful and Perfect Names of Allah” — Shaykh as-Sa’di (d.1376H)